Archive for the 'Body' Category

In fact, what’s truly amazing about the work is that scientists are able to actually measure these very low levels of radiation at all — as well as to chemically fingerprint them and thereby prove that certain radioisotopes of the chemical element Cesium, which arise as a by-product of nuclear fission, actually arrived off of North American waters after traveling all the way from Fukushima.

The big non-news is that the radiation levels are small — hence the amazement at being able to measure them. But say “radiation” and some fraction of the population freaks right the hell out. So that’s the take-home message, even if there are a few subtle things missing in the story.

The activity (how radioactive a sample is, measured these days in Becquerels, or number of decays per second) is not the whole story, because not all radiation damages the body the same amount, and it matters greatly if the contamination accumulates in the body or not. Their example is swimming in the ocean, but I think people might also be concerned about eating fish, who would effectively be filtering out and accumulating radioactive material. Are they twice as radioactive as the water? Ten times? Is the internal dose more damaging than an external dose (that’s true of alpha and beta radiation)? Cs-137 is a beta emitter, and in humans it accumulates in the body, with a biological half-life of 70 days. So I imagine it accumulates in fish, as well. But with such low starting levels, probably not anything to worry about.

Another nit is with the picture down near the end, the “helpful figure from the Woods Hole Oceanographic Institution” is somewhat less helpful than it could be. First of all, it doesn’t have the Fukushima incident on it as a comparison. I’ve seen a few links, and their estimates vary by around an order of magnitude, but it’s between ~4 million and ~40 million curies of Iodine and Cesium into the atmosphere, and one link had an additional amount going into the water of half of the atmospheric discharge. So there’s your comparison. (A curie is 3.7 x 10^10 decays per second, as that was Marie Curie’s favorite number is that activity of a gram of Ra-226. But it’s a huge number and not normally useful for everyday discussion — you are usually talking about picocuries or nanocuries, or something like that.)

Another nit is that comparing activities between different isotopes is a tad dicey, for a couple of reasons. The activity is a rate, not the total amount of potential dose. 1 curie of a contaminant that has a half-life of a day is very different than a curie of something else that has a half-life of a million years — in 10 days, the one-day half-life isotope is down to 0.1% of the activity (a millicurie), while the other is still basically the same. When you look at the Uranium and Potassium numbers on that infographic, keep in mind that K-40 has a half-life of 1.3 Billion years, and Uranium-238 is 4.5 Billion years. Their respective activities aren’t going to perceptibly change in the next 30 years, while any contaminant Cs-131 will drop in half. Further, Uranium is an alpha decayer, which is the most damaging internal source (though if it’s external is pretty harmless — an alpha won’t penetrate your clothes or through the dead layer of skin on your body). Uranium also decays through a chain of radioactive daughters, which have their own decays to contribute. So the activity doesn’t tell the whole story — the reason the ocean’s Uranium and Potassium aren’t a big issue is that the ocean is huge. Fukushima’s release was concentrated, but owing to time and dilution, it’s not a problem for those of us in the US.

Scaling laws, related to why kids may be better off with mittens, and why cold fingers on a child also tells us we won’t be attacked by giant ants.

Now, my daughter is significantly smaller than me, so overall she gets colder more quickly anyway. And, given that “Gloves that work” features on her Christmas list, an equally valid answer to her question could have been “Because you need better gloves, and I’m a bad dad.” But the physics happens too.

Swinging the arms clearly saves energy for runners, and helps to minimise the amount that we rotate the body while swinging our legs, which led Arellano and Kram to wonder whether the metabolic benefits of arm swinging outweigh the cost of carrying the limbs.

I hold degrees in physics and have spent a lot of time learning and teaching quantum mechanics. Nonphysicists seem to have the impression that quantum physics is really esoteric, with those who study it spending their time debating the nature of reality. In truth, most of a quantum mechanics class is lots and lots of math, in the service of using a particle’s quantum state—the bundle of physical properties such as position, energy, spin, and the like—to describe the outcomes of experiments. Sure, there’s some weird stuff and it’s fun to talk about, but quantum mechanics is aimed at being practical (ideally, at least).

Yet the mysterious aspects of quantum physics and consciousness have inspired many people to speculate freely. The worst offenders will even say that because we don’t fully understand either field, they must be related problems. It sounds good at first: We don’t know exactly how some things in quantum physics work, we don’t know exactly how to go from the brain to consciousness, so maybe consciousness is quantum.

Having endured plaster and fiberglass casts in my youth (when my ego, overestimating my limited athletic ability, was writing checks my body couldn’t cash), I can say that even if the ultrasound part of this is not effective, having a cast where the limb can “breathe” would be a huge win, in terms of bathing and accessing itchy areas.

They only mention building materials in the paper’s abstract, so this ignores C-14 decay, which is important because people are radioactive, too — any accounting of the radioactivity of a room should be compared with what you can’t avoid because it’s an internal dose.

James Bond’s famous catchphrase “shaken, not stirred” may have stemmed from his inability to stir his drinks due to an alcohol-induced tremor affecting his hands, researchers reveal in a new, tongue-in-cheek medical report.

Such a tremor would be likely in a spy who drank more than four times the recommended limit of alcohol throughout his missions, they said, writing in a special Christmas issue of the BMJ — a lighthearted edition of the medical journal that includes real research.

As the HuffPo notes, this is not serious (though this has gotten a lot of play and not all articles make this observation), but I’m going to be a killjoy anyway and apply Betteridge’s Law: the answer is no.

It’s not because of the silliness of applying medical analysis to a frikkin’ fictional character, or that the fictional data is anecdotal in nature, or even that the fictional empirical evidence says no, because Bond was a crack shot with his pistol. It’s because Bond was ordering the drinks, not mixing them himself. A tremor is moot.

But there’s more to this. One version I read (and unfortunately I can’t find the link to the specific article, but several versions are out there) included a description that a properly mixed martini would be stirred, and with a thin wooden spoon, rather than a metal one which would raise the temperature of the drink. This is baloney, but probably a case of right answer, wrong reason. The reasoning is wrong, because the drink is mixed with ice, so the final temperature is going to be the same — probably the temperature of the ice cubes.

I say probably because this is most likely not the case like where you have a pure water/ice mixture, which stays at 0 ºC because of the phase change going on. In the drink you will have a mixture or alcohol and water, and the freezing point will be lower. For a 50/50 mix, the freezing point will be -32 ºC, and the ice is probably warmer than that — freezers don’t generally get that cold. (dissolving things in water lowers the freezing point, and this is a colligative property, meaning it depends on how much stuff you have dissolved. It’s why putting salt on ice tends to melt it if you’re near 0 ºC: there’s always a little water, and when the salt dissolves the solution freezes at a lower temperature, which allows the ice to melt)

If the final temperature is independent of the spoon type, then what’s right about this? The metal spoon will absorb more energy from the solution, so while the final temperature is unaffected, this will tend to melt more of the ice, and that will water down the drink. From a thermodynamic standpoint that is more likely why you want to use a wooden spoon. Some years ago there was an episode of the West Wing where the president was complaining about “shaken, not stirred” in the context that shaking makes the ice chip, and small chips won’t get strained out when you pour the drink, which also has the effect of watering the drink down.

All of this reminds me that my parents used to complain about “shaken, not stirred” when we’d see these movies on TV. My dad was a bartender at one point, and the complaint (from both) was that shaking would bruise the alcohol. I knew enough science to know that this could not be literally true, but I never got an explanation of what “bruising” really was; I assumed that it was a euphemism for something undesirable and left it at that. Now that the internet exists, I can find something calling itself the martini FAQ and see that this is a matter of aeration.

Another addendum to this is that the link I can’t find had in it a link to some martini information, in which it was claimed that a dry martini had a lot of dry vermouth in it, but claimed that recently this had changed to mean very little (or no) vermouth. Well, that doesn’t jibe with the bartender joke I know where someone asks for a dry martini and the bartender asks how dry they want it. To which the customer responds, “Just whisper ‘vermouth’ over the glass.” That joke is probably older than I am, so no vermouth = dry is not a recent trend.

I had noted a long time ago that based on the proposed mechanism, there was no basis to expect magnetic bracelets to work. No real surprise that they don’t.

The research published in PLOS ONE, show that both the standard magnetic wrist strap and the copper bracelet provided no meaningful therapeutic effects beyond those of a placebo, which was not magnetic and did not contain copper.

Neither the story nor the referenced study mention if the lasers are all supposed to be 5 mW and thus class IIIa (or 3R), or if, as one link claims, there are higher-power lasers that aren’t limited by this threshold because they aren’t marketed as laser pointers. Or if the violation isn’t that they are claiming 5 mW and exceeding it, but rather they are incorrectly (and presumably illegally) calling the more powerful devices laser pointers and listing them as class III/3R.

Then there was this claim.

Green lasers use a shorter wavelength of light than red ones, making them brighter and more dangerous.

This was lifted from the included link, but lacking the detail found in another link. Green lasers aren’t brighter simply because they have a shorter wavelength. If that were true, a blue laser would be brighter still, and they aren’t. In fact green lasers must fire fewer photons per second at you than red lasers do, if they all have the same power. What makes the green brighter is your eye. The eye’s response to light isn’t constant across the spectrum — it’s much better at absorbing (and thus detecting) green light then either red or blue, so the green light has a better chance at doing damage.

Green could help physicians see better for two reasons. First, looking at blue or green can refresh a doctor’s vision of red things, including the bloody innards of a patient during surgery. The brain interprets colors relative to each other. If a surgeon stares at something that’s red and pink, he becomes desensitized to it. The red signal in the brain actually fades, which could make it harder to see the nuances of the human body. Looking at something green from time to time can keep someone’s eyes more sensitive to variations in red

I’ve noticed the opposite effect in the lab; when I work with lasers I wear laser safety glasses, which block the wavelength being used, and for quite a while this has been in the NIR. The glasses block everything above ~650 nm, so the glasses look bluish-green and deprives your eyes of any red light. After taking them off, everything has a pink hue to it.

“There are numerous different kinds of synaesthesia,” Professor Brogaard began. “One of the most common forms is grapheme-colour synaesthesia, which is where letters or numbers give rise to specific colours. There are people who have so-called mirror-touch synaesthesia who experience the feeling of being touched when they see other people being touched. There are others who see colours when they taste something and some people even see colours when they feel fear.”